Many applications require coherent combination of two or more lasers producing a single collimated, coaxial beam. These range from experiments in nonlinear optics (e.g., difference-frequency mixing) to spectroscopy applications such as Coherent Anti-stokes Raman Spectroscopy (CARS). Other applications requiring high brightness can also benefit from the optical power addition of combining beams. Beam arrays are an example of a solution to high brightness using multiple beam sources. Beam arrays using multiple beams that are spatially located close to each other, but are not coaxial, do not produce a coherently combined beam, which will have a very poor beam quality.